Nowadays, there is a major need to abbreviate and improve current laboratory procedures for the detection and most of all susceptibility evaluation of microorganisms. An ideal diagnostic technology would give susceptibility profile timely in order to allow the institution of appropriate therapy based on it.
In the case of the most serious infections associated namely to septic shock, speed is of the essence. It has been shown that the risk of mortality would increase substantially by the hour if appropriate antimicrobial therapy is delayed.
The current gold-standard diagnostic methods are based on culture which is slow, labour intensive, providing phenotypic identification and antimicrobial susceptibility testing, requiring 48-72 h after collection of the samples. Empiric therapy has to be initiated often with a large spectrum antibiotic, leading to the increase of antimicrobial resistance.
Using classic tests, biological products like urine have to be cultivated in solid media and only then identification and susceptibility evaluation could take place. Blood are usually inoculated on broth media (blood cultures) and analysed automatically; when become positive they are plated on solid media and only after 24 h at least, colonies are formed for the susceptibility evaluation. On the other hand another 24 h are necessary for susceptibility profile determination as they are based on the ability to grow in the presence of a panel of drugs.
Clinical resistance could be related to lack of antimicrobial susceptibility of the strain but also to low levels of active antimicrobial drug on infection local. Biochemical protocols are available for only few drugs e.g. vancomycin, gentamicin or amikacin and they could be inactive.